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Date: Wed, 07 Oct 2015 11:23:52 +0100
From: Marc Zyngier <marc.zyngier@....com>
To: "Suzuki K. Poulose" <suzuki.poulose@....com>,
linux-arm-kernel@...ts.infradead.org
CC: linux-kernel@...r.kernel.org, Catalin.Marinas@....com,
Will.Deacon@....com, Mark.Rutland@....com,
kvmarm@...ts.cs.columbia.edu, kvm@...r.kernel.org,
ard.biesheuvel@...aro.org, christoffer.dall@...aro.org
Subject: Re: [PATCH 12/15] arm: kvm: Move fake PGD handling to arch specific
files
On 15/09/15 16:41, Suzuki K. Poulose wrote:
> From: "Suzuki K. Poulose" <suzuki.poulose@....com>
>
> Rearrange the code for fake pgd handling, which is applicable
> to only ARM64. The intention is to keep the common code cleaner,
> unaware of the underlying hacks.
>
> Cc: kvmarm@...ts.cs.columbia.edu
> Cc: christoffer.dall@...aro.org
> Cc: Marc.Zyngier@....com
> Signed-off-by: Suzuki K. Poulose <suzuki.poulose@....com>
> ---
> arch/arm/include/asm/kvm_mmu.h | 7 ++++++
> arch/arm/kvm/mmu.c | 44 +++++---------------------------------
> arch/arm64/include/asm/kvm_mmu.h | 43 +++++++++++++++++++++++++++++++++++++
> 3 files changed, 55 insertions(+), 39 deletions(-)
>
> diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
> index 405aa18..1c9aa8a 100644
> --- a/arch/arm/include/asm/kvm_mmu.h
> +++ b/arch/arm/include/asm/kvm_mmu.h
> @@ -173,6 +173,13 @@ static inline unsigned int kvm_get_hwpgd_size(void)
> return PTRS_PER_S2_PGD * sizeof(pgd_t);
> }
>
> +static inline pgd_t *kvm_setup_fake_pgd(pgd_t *pgd)
> +{
> + return pgd;
> +}
> +
> +static inline void kvm_free_fake_pgd(pgd_t *pgd) {}
> +
> struct kvm;
>
> #define kvm_flush_dcache_to_poc(a,l) __cpuc_flush_dcache_area((a), (l))
> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
> index 7b42012..b210622 100644
> --- a/arch/arm/kvm/mmu.c
> +++ b/arch/arm/kvm/mmu.c
> @@ -677,43 +677,11 @@ int kvm_alloc_stage2_pgd(struct kvm *kvm)
> * guest, we allocate a fake PGD and pre-populate it to point
> * to the next-level page table, which will be the real
> * initial page table pointed to by the VTTBR.
> - *
> - * When KVM_PREALLOC_LEVEL==2, we allocate a single page for
> - * the PMD and the kernel will use folded pud.
> - * When KVM_PREALLOC_LEVEL==1, we allocate 2 consecutive PUD
> - * pages.
> */
> - if (KVM_PREALLOC_LEVEL > 0) {
> - int i;
> -
> - /*
> - * Allocate fake pgd for the page table manipulation macros to
> - * work. This is not used by the hardware and we have no
> - * alignment requirement for this allocation.
> - */
> - pgd = kmalloc(PTRS_PER_S2_PGD * sizeof(pgd_t),
> - GFP_KERNEL | __GFP_ZERO);
> -
> - if (!pgd) {
> - kvm_free_hwpgd(hwpgd);
> - return -ENOMEM;
> - }
> -
> - /* Plug the HW PGD into the fake one. */
> - for (i = 0; i < PTRS_PER_S2_PGD; i++) {
> - if (KVM_PREALLOC_LEVEL == 1)
> - pgd_populate(NULL, pgd + i,
> - (pud_t *)hwpgd + i * PTRS_PER_PUD);
> - else if (KVM_PREALLOC_LEVEL == 2)
> - pud_populate(NULL, pud_offset(pgd, 0) + i,
> - (pmd_t *)hwpgd + i * PTRS_PER_PMD);
> - }
> - } else {
> - /*
> - * Allocate actual first-level Stage-2 page table used by the
> - * hardware for Stage-2 page table walks.
> - */
> - pgd = (pgd_t *)hwpgd;
> + pgd = kvm_setup_fake_pgd(hwpgd);
> + if (IS_ERR(pgd)) {
> + kvm_free_hwpgd(hwpgd);
> + return PTR_ERR(pgd);
> }
>
> kvm_clean_pgd(pgd);
> @@ -820,9 +788,7 @@ void kvm_free_stage2_pgd(struct kvm *kvm)
>
> unmap_stage2_range(kvm, 0, KVM_PHYS_SIZE);
> kvm_free_hwpgd(kvm_get_hwpgd(kvm));
> - if (KVM_PREALLOC_LEVEL > 0)
> - kfree(kvm->arch.pgd);
> -
> + kvm_free_fake_pgd(kvm->arch.pgd);
> kvm->arch.pgd = NULL;
> }
>
> diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
> index 6150567..2567fe8 100644
> --- a/arch/arm64/include/asm/kvm_mmu.h
> +++ b/arch/arm64/include/asm/kvm_mmu.h
> @@ -198,6 +198,49 @@ static inline unsigned int kvm_get_hwpgd_size(void)
> return PTRS_PER_S2_PGD * sizeof(pgd_t);
> }
>
> +/*
> + * Allocate fake pgd for the page table manipulation macros to
> + * work. This is not used by the hardware and we have no
> + * alignment requirement for this allocation.
> + */
> +static inline pgd_t* kvm_setup_fake_pgd(pgd_t *hwpgd)
> +{
> + int i;
> + pgd_t *pgd;
> +
> + if (!KVM_PREALLOC_LEVEL)
> + return hwpgd;
> + /*
> + * When KVM_PREALLOC_LEVEL==2, we allocate a single page for
> + * the PMD and the kernel will use folded pud.
> + * When KVM_PREALLOC_LEVEL==1, we allocate 2 consecutive PUD
> + * pages.
> + */
> + pgd = kmalloc(PTRS_PER_S2_PGD * sizeof(pgd_t),
> + GFP_KERNEL | __GFP_ZERO);
> +
> + if (!pgd)
> + return ERR_PTR(-ENOMEM);
> +
> + /* Plug the HW PGD into the fake one. */
> + for (i = 0; i < PTRS_PER_S2_PGD; i++) {
> + if (KVM_PREALLOC_LEVEL == 1)
> + pgd_populate(NULL, pgd + i,
> + (pud_t *)hwpgd + i * PTRS_PER_PUD);
> + else if (KVM_PREALLOC_LEVEL == 2)
> + pud_populate(NULL, pud_offset(pgd, 0) + i,
> + (pmd_t *)hwpgd + i * PTRS_PER_PMD);
> + }
> +
> + return pgd;
> +}
> +
> +static inline void kvm_free_fake_pgd(pgd_t *pgd)
> +{
> + if (KVM_PREALLOC_LEVEL > 0)
> + kfree(pgd);
> +}
> +
> static inline bool kvm_page_empty(void *ptr)
> {
> struct page *ptr_page = virt_to_page(ptr);
>
Reviewed-by: Marc Zyngier <marc.zyngier@....com>
M.
--
Jazz is not dead. It just smells funny...
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